Document Type
Conference Paper
Publication Date
2012
Abstract
A key objective of this paper is to share application of chilled water sprays for prevention of frictional ignitions in coal mines to provide a safe occupational environment. Frictional ignitions in underground mines if not managed adequately may lead to major explosions. Historic statistics have indicated that the greatest explosion risk originates from frictional ignitions. Methane and dust related to explosions have resulted in over 7500 lives lost in the last ten years worldwide. The experiences of chilled water sprays used for managing heat in deep metal mines in South Africa is highly relevant to frictional incendive/face heat management in Australian coal mines. Mine ventilation and water sprays (used for dust suppression and dilution ventilation) are established technologies that are widely used in coal mines for the prevention of frictional ignitions. However, greater benefits of cooling or the sharp reduction in incendive heat from cutting picks by the use of chilled water sprays outweighs cooling using the current practice of using warm service water. Chilled water spray droplets have the potential to become „improved last line of defense‟ against gas ignitions. For example, introduction of chilled water sprays with millions of fine chilled water droplets around picks and face area would provide a simple, reliable and rapid cooling power of 210 kW and 1 005 kW for continuous miners faces and Longwall shearer face respectively. A US study has noted that 90% of all frictional ignitions occurred in coal mines that liberated at least 0.39% of CH4 through their mine ventilation air methane system. However, analyses of South African statistics indicate that frictional ignition have occurred in coal and gold mines that liberated even with lower emissions between 0.02% to 0.05% of CH4 through their mine ventilation air methane system. Therefore, it is important to raise awareness that frictional ignition risks are ever present in coal mines regardless of gas contents or gas emissions. The application of wet head systems, proactive ventilation and methane monitoring, active suppression systems, and frequent safety interactions for preventing frictional ignitions are discussed.
Publication Details
B. Belle, D. Carey and B. Robertson, Prevention of frictional ignition in coal mines using chilled water sprays, 12th Coal Operators' Conference, University of Wollongong & the Australasian Institute of Mining and Metallurgy, 2012, 175-184.